Due to the beneficial effects of natural daylight on human physiology and cognitive sensing architecture has been striving for some time to guide sunlight as deeply as possible into the interior of buildings in order to have a maximum of daylight even in rooms which are located in the interior side of a building and to require a minimum of artificial light.
In order to achieve introduction of sunlight into the interior of a building for example so called light tubes have been proposed which essentially consists of cylindrical tubes having mirrored internal walls for conducting daylight deeply into the interior of a building with minimal loss. However, efficiency of such light tubes depends on the position of the sun and will be especially compromised during evening hours or during early morning hours.
On the other hand heliostats have been proposed which by way of deflection surfaces deflect and occasionally even focus the daylight into the desired direction in order to conduct a strong bundle of light into the interior of the building. Such heliostat systems usually are very elaborate, spacious and costly. DE 101 29 745 A1 for example discloses a light guide device of the kind referred to above wherein sunlight is guided onto a second parabolic mirror which will conduct the deflected light into the interior of the building by way of a swivelable and rotatable first mirror. A Fresnel lens is interposed between them to focus the light in front of the parabolic mirror.